Evaluation of selected watershed assessment techniques.

Abstract

Watershed assessment methods are used in natural resource management to monitor and assess watershed conditions. Many assessment methods are available for these purposes, however, most have not been evaluated to determine their effectiveness. Additionally, most methods require comparisons with references sites. These are often difficult to select due to past disturbances, and spatial or temporal changes. This study attempts to address these issues. Three watershed assessment methods, channel geomorphic analysis, zigzag pebble count, and thalweg-watershed area link (T-Walk), were chosen for evaluation based on results from a Delphi study. Data were collected from five small perennial streams in east central Arizona. Statistical analyses were used to compare methods and to develop stream-watershed relationships based on field-collected stream data and GIS-derived watershed parameters. From these relationships, prediction models were developed for use in selecting reference sites. Strong multiple regression models were developed to explain channel cross-sectional area and particle size, D₅₀.